CuCr Contact Disc
The CuCr contact disc is the geometry that does the work inside a vacuum interrupter.
Copper chromium is the standard contact material for medium-voltage vacuum interrupters. Inside a vacuum circuit breaker or vacuum contactor, the pair of contacts that make and break the circuit under vacuum are almost always CuCr. The copper matrix carries continuous current, and the chromium phase handles the arc during interruption, suppresses contact welding, and keeps the chopping current low. Where CuW (copper tungsten) dominates in SF6, oil, and air-insulated MV switchgear arcing contacts, CuCr dominates inside the vacuum bottle. We supply CuCr contacts in the grades covered by GB/T 26867-2011 (Chinese national standard for copper-chromium electrical contacts) : CuCr25 for high-conductivity general-purpose vacuum interrupter duty, and CuCr50 for higher-rated, high-cycle, and severe interruption duty where anti-weld behavior and low chopping current matter most. Contacts are produced as discs and custom geometries to drawing, in axial-magnetic-field (AMF) and radial-magnetic-field (RMF) forms.
The CuCr contact disc is the geometry that does the work inside a vacuum interrupter.
CuCr custom component is the catch-all listing for copper-chromium parts that don't fit the standard disc, AMF, or RMF contact forms.
CuCr25 is the high-conductivity copper-chromium grade, 25% chromium in a copper matrix, and the most common contact material for general-purpose medium-vol...
CuCr50 is the high-chromium copper-chromium grade, 50% chromium in a copper matrix, for vacuum interrupters with severe interruption duty.
Copper chromium exists for one job: the make-and-break contact pair sealed inside a vacuum interrupter. Outside the bottle it has no advantage over copper, and it is not a substitute for CuW on arc-exposed surfaces in air, oil, or SF6.
Three properties earn it that place. The chromium phase getters residual gas and helps hold the vacuum. It suppresses contact welding after a close onto a fault. And it keeps chopping current low, which is what protects motor and transformer windings from switching overvoltages when the breaker opens a small inductive current.
| Grade | Chromium | Typical use |
|---|---|---|
| CuCr25 | 25 wt% | The high-conductivity grade and the default for general-purpose MV vacuum interrupter duty |
| CuCr50 | 50 wt% | Higher-rated, high-cycle, and severe interruption duty, where anti-weld behaviour and low chopping matter most |
Both grades are supplied per GB/T 26867-2011, the Chinese national standard for copper-chromium electrical contacts.
The contact material is only half the specification. The disc geometry controls how the arc behaves across the face, and it comes in two families.
AMF — axial magnetic field. Slots or a coil behind the face drive the arc into a diffuse mode spread across the whole contact. Lower erosion per operation, and the usual choice at higher interrupting ratings.
RMF — radial magnetic field. Spiral or cup geometry drives the arc to rotate around the face so no single spot takes the whole duty. Simpler and cheaper, common at distribution ratings.
An AMF contact and an RMF contact of the same diameter and grade are not interchangeable. The interrupter was designed around one of them.
If the contact lives inside a vacuum bottle, CuCr. If it is an arcing contact in air, oil, or SF6, CuW. The material comparison covers the cases in between, including the arc contacts fitted around a vacuum interrupter.
No. We supply the contact material and machined contact parts. Bottle assembly, sealing, and evacuation stay with the interrupter manufacturer.
A drawing, the grade, and whether the geometry is AMF or RMF. If the interrupter rating is known, state it — it is the fastest cross-check that the grade and geometry on the drawing match each other.